from what i've read when i used a thumbdrive to install windows 8 that some bios can handle booting from a thumbdrive/sd card and others can't. it could also do with the motherboard you are using.
The issue with installing from media other than disk (HDD, SSD, CD/DVD/BD) is that those formats generally are not designed to be booted from. Most motherboards, if not all, have options for alternative medias (such as USB drives) in their bootload order, one still has to configure the USB drive/SD card to be bootable. That requires configuring the partition table properly. Alternatively, you can use programs designed specifically for such instances. For example, if one were to do a Debian Live CD install from a USB drive, said individual could use unetbootin (apt-get install unetbootin).
As for an SD card, I would strongly recommend against using such media for said purposes. As I said before, if you want the SD card to live a long and happy life, such read/write accesses would be bad for it's longevity. Instead, I would recommend using a USB drive, which is designed to handle such loads, and tends to be cheaper than SD cards.
Of course, the final and ultimate solution is to use a DVDR. Or, if you have the means, do a netinstall.
